Ignore the usb part of the tomatousb name. The name is simply an historical artifact.
USB may have been the initial motivation for this mod but over the last several years many, many additional features unrelated to usb have been added to the very good base of tomatousb. There is no reason to prevent it from being used on routers without usb ports. You seem to get hung up on inconsequential things.
btw, there is no way the firmware could be named in such a way that the name contained all of the features.
If this issue bothers you then don't use the firmware. You are not the target user base.
Also, ASUS makes great routers. Among the experts, they are often the favorite. The RT-N16 is a bit old now and lacks hardware support for the 5 GHz range but is/was one of the very best for its time. I have one as do many others that use tomatousb.